(a) Technical Field
The present invention relates to an engine operation control system and method of an eco-friendly vehicle, and more particularly, to an engine operation control system and method of an eco-friendly vehicle, which achieve optimal engine operation efficiency by changing a region using an engine operating point based on a battery state of charge (SOC) region and a driver requirement torque.
(b) Background Art
Hybrid vehicles and plug-in hybrid vehicles are types of eco-friendly vehicles which employ a motor as well as an engine as a power source to reduce exhaust gas and to enhance fuel efficiency and include a power transmission system installed therein, which separately transfers engine or motor power to driving wheels or transfers engine and motor power together to the driving wheels. An engine system of a hybrid vehicle may also include an exhaust gas recirculation (EGR) device installed therein to reduce exhaust gas and to enhance fuel efficiency.
A driving mode of the hybrid vehicle may include an electric vehicle (EV) in which the vehicle is driven by a driving force of a motor, a hybrid electric vehicle (HEV) mode in which the vehicle is driven by both driving forces of an engine and a motor, an engine exclusive mode in which the vehicle is driven by engine driving force.
An engine operating point of the hybrid vehicle may vary based on a driver requirement torque and a current vehicle battery state of charge (SOC), but there is a need to control an optimal engine operating point in which a minimum battery SOC discharge amount is consumed. In addition, when an operation of the EGR is repeatedly started and released based on variations of the engine torque, efficiency for reducing exhaust gas may be degraded and fuel efficiency may also be degraded, and thus there is a need to control an optimal engine operating point when the EGR is operated.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.